1. Field of the Invention
The present invention relates to an optometry apparatus capable of performing a cross cylinder test for examining an astigmatic state of an eye to be examined.
2. Description of the Related Art
An optometry apparatus capable of performing a cross cylinder test has been known as an optometry apparatus for optometry measurement. For example, an optometry apparatus described in JP 2004-180955 A (claims and paragraphs [0030] and [0039] to [0047] of the specification) includes an operating means such as a joystick lever and a computer having a computer program for automatically performing an eye examination. An objective eye examination can be simultaneously performed for both eyes. In addition, a subjective eye examination can be performed by a person to be examined alone using a screen navigation system or a voice navigation system. The cross cylinder test is performed during the flow of those examinations.
The optometry apparatus described in JP 2004-180955 A is constructed so as to provide training screens for training an operating method for examination before an actual examination is performed. Training of the cross cylinder test is also performed using the training screens. In the cross cylinder test, an index S shown in FIG. 16 (which is called a cross cylinder test chart or the like) is indicated to an eye to be examined. Astigmatic power or an astigmatic axial angle is switched from one to another, and the person to be examined makes a comparative determination of appearance states of the index S, thereby examining an astigmatic state of the eye to be examined. However, a difference between the appearance states to be compared is not very clear. Therefore, on a training screen, a typical difference between appearance states caused when the astigmatic axial angle is changed is presented in an exaggerated manner. One projection image is clearly displayed on the training screen and the other projection image is displayed thereon with a blurred state, thereby promoting understanding of the contents of the cross cylinder test and understanding of the operating method.
However, when the training is performed before the examination, it is likely that the person to be examined will forget the examination contents and the operating method because some time is elapsed before the actual cross cylinder test starts. The training requires time, so there is a problem in that an examination time per a person to be examined becomes longer.
In the cross cylinder test, a difference between appearance states of the index to be compared is not clear and thus it is difficult for the person to be examined to make rapid determination, so that a time for the cross cylinder test lengthens in some cases. In particular, there are cases where the astigmatic axial angle is measured with excessive measurement precision, which hinders the smooth progress of the cross cylinder test. The astigmatic axial angle measurement performed through the cross cylinder test is to compare appearance states of a pair of projection images of the cross cylinder test chart S with each other, so the measurement is in some cases completed with a state in which the projection image are not clearly visually recognized. Therefore, the response given by the person to be examined at the last stage of the test often becomes vague, leading to an increase in examination time.